1. Field of the Invention
The present invention relates to a printer, and more particularly to an impact printer having a mechanism for erasing a printed character with an erasing ribbon for correction.
2. Description of the Prior Art
In a prior art typewriter, when a printed character is to be erased, a print head is moved to the character to be erased and a type corresponding to that character is impacted through an erasing ribbon in response to an erase command. The erasing ribbon is an adhesive tape or a tape having a coating material of the same color as that of a print paper applied on a back side thereof. In the former case, ink of the printed character is removed from the print paper, and in the latter case the character is overprinted, to erase the printed character.
In such a prior art printer having an overprint type erasing mechanism as shown in U. S. Pat. No. 4,307,971, the precision of movement of a lateral drive mechanism of a carriage is not high and an unerased indicia often remains due to hysteresis and vibration of the carriage drive mechanism. When a character is printed over the correction area, it is overlapped with the unerased indicia and very poor finishing is presented.
If precision of operation of the drive mechanism is to be improved in order to perfectly erase the character by the overprint erasing mechanism, the manufacturing cost of the device will remarkably increase.